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Design of polygalacturonate hydrogels using iron (II) as cross-linkers : A promising route to protect bioavailable iron against oxidation

Abstract : We designed stable and highly reproducible hydrogels by external unidirectional diffusion of Fe2+ ions into aqueous solutions of polygalacturonate (polyGal) chains. The Fe2+ ions act as cross-linkers between the Gal units in such a way that both the molar ratio R ([Fe2+]/[Galunits]=0.25) and the mesh size of the polyGal network at the local scale (zeta=75 +/- 5 angstrom) have constant values within the whole gel, as respectively determined by titration and Small Angle Neutron Scattering. From macroscopic point of view, there is a progressive decrease of polyGal concentration from the part of the gel formed in the early stages of the gelation process, which is homogeneous, transparent and whose Young modulus has a high value of similar to 10(5) Pa, up to the part of the gel formed in the late stages, which is heterogeneous, highly turbid and has a much lower Young modulus of similar to 10(3) Pa. Since the local organization of the polyGal chains remains identical all along the hydrogels, this macroscopic concentration gradient originates from the formation of heterogeneities at a mesoscopic length scale during the gelation process. In addition, X-ray Absorption Spectroscopy measurements remarkably reveal that Fe2+ ions keep their +II oxidation state in the whole gels once they have cross-linked the Gal units. These polyGal hydrogels thus protect iron against oxidation and could be used for iron fortification.
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https://hal-univ-bourgogne.archives-ouvertes.fr/hal-01895553
Contributeur : Pam - Université de Bourgogne <>
Soumis le : lundi 15 octobre 2018 - 12:23:47
Dernière modification le : lundi 19 octobre 2020 - 14:26:01

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Ali Maire Du Poset, Adrien Lerbret, Andrea Zitolo, Fabrice Cousin, Ali Assifaoui. Design of polygalacturonate hydrogels using iron (II) as cross-linkers : A promising route to protect bioavailable iron against oxidation. Carbohydrate Polymers, Elsevier, 2018, 188, pp.276 - 283. ⟨10.1016/j.carbpol.2018.02.007⟩. ⟨hal-01895553⟩

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